Coated sheet material and article made therefrom



Patented June 10, 1941 COATED SHEET MATERIAL AND ARTICLE MADE THEREFROM Floyd E. Williams, Gary, Ind., assignor to Marbon Corporation, Chicago, Ill., a corporation of Delaware No Drawing. Application April 22, 1937, Serial No. 138,366. Renewed November 15, 1939 8 Claims. (Cl. 229-55) This invention relates to coated sheet material and to articles of manufacture made therefrom. More particularly, it relates to coated paper, and to paper receptacles made from such coated An object of this invention is to provide a relatively impermeable flexible coated paper which remains impermeable after creasing, and which remains flexible and impermeable over a prolonged period of time.

Another object of 'this invention is to provide an oil resistant flexible coated paper which remains oil resistant after creasing.

A further object is to provide a moisture and vapor resistant coated paper which will remain moisture and vapor resistant after creasing.

Another object is to provide a thin flexible translucent or transparent sheet material suitable for wrapping greases, fats, foodstuffs and the like.

Another object is to provide a paper bag of the ordinary creased type which will hold cold or warm petroleum oils without leakage over periods of time necessary for commercial usage.

A further object is to provide a sealed, flexible, paper package such as a sealed bag, which will retain products without leakage and maintain the product in substantially its original uncontaminated, fresh condition over the prolonged periods of timeof commercial use.

Features of my coated sheets are their impermeablllty before and after the sheets are creased, land the flexibility of the sheets combined with toughness, strength, and tear resistance, over prolonged periods of time.

Other objects and features of this invention will become apparent from the accompanying specification, and claims.

Hitherto attempts to obtain a highly oil resistant, moisture, and vapor resistant flexible sheet by coating paper have only been partially successful. For some purposes fair results have been attained, but when bags or other creased receptacles were made from such sheets and fllled with oils and the like, there was generally trouble due to leakage at the crease, and/or at the-seal.

In' the application of Gebauer Fuelnegg and Eugene w. Moffett, Serial Ho. 122,252, flied April 25, 1934, now Patent 2,140,835, there are dis- .closed coated paper sheets of superior resistance .to watenwater vapor and grease, on which the present invention is, however, an improvement.

. I have discovered that superior results are at- -talned if a paper sheet such asglassine, parchment, or indeed any sulphite or kraft paper is plasticized before coating it with a film of a rubber compound or derivative.

In a preferred embodiment of my invention, paper is given a plasticization with glycerine until the glycerine is present in the paper in amount above 5%, and preferably to a point where the paper is substantially saturated with the glycerine uniformly throughout its thickness. In this manner the paper is made translucent and also sufllciently flexible so it will not crack to any appreciable extent on creasing.

However, it has been found that this paper, of itself, while of good oil resistance for many purposes, is not entirely suitable for the use in bags which must hold oil over prolonged periods of time. Pinholes are present in the paper and are particularly prevalent along the creases in spite of the high degree of glycerination. In accordance with my invention, therefore, I coat such a plasticized paper with a flexible oil, water, and glycerine resistant film of a rubber derivative such as a rubber hydrohalide.

Various types of paper may be used in my invention, including parchment, glassine, kraft, and ordinary sulphite paper. An unsized paper free from solid fillers is preferred. Where transparency is desired, a glassine is preferred. A parchment paper of the type obtained by treating sulphite paper with sulfuric acid has been found particularly suitable where high strength is desired. It has high wet strength, is not weakened by glycerine, and will retain tenaciously large amounts of plasticizer. There appears, also, to be something in the chemical nature of vegetable parchment that makes it particularly suitable with rubber hydrochloride. Kraft paper also has good strength when plasticized and gives highly satisfactory results when coated with rubber hydrochloride.

The plasticizer for the paper is chosen according to its oil resitsance, ease of incorporation, retainability in the paper, flexibility efIect, and cost. Glycerine is oil repellent, and because of its water solubility is readily incorporated in paper, well retained, and gives flexibility not only of itself but because of water which it absorbs.

Other plasticizers which act similar to glycerine are polyglycerols, ethylene glycol, triethylene glycol, and triethanol amine.

The amount of plasticizer required will vary according to the use of the'paper, and also will paper is to be used in the manufacture of creased bags suitable for the shipment and storage of oil, the amount of plasticization should be over I 5% by weight of the paper, up to the point where the paper is substantially saturated with plasticizer. In the case of vegetable parchment, very high proportion of glycerine and like plasticizers can be used without weakening the paper, and the preferred amount of plasticizer is such that the paper is substantially saturated. Kraft paper is similar to parchment in its ability to maintain its strength after incorporation of large quantities of hygroscopic plasticizers.

After considerable experimentation, it was found that compositions containing rubber hydrochloride as a base were the most suitable for coating on plasticized paper. Solutions of rubber hydrochloride are not compatible with glycerine or like plasticizers so that solutions of rubber r hydrochloride will form a thin uniform surface film on the glycerinated paper, and extend through pinholes in the glycerinated paper without being absorbed or attacked by the glycerine. Moreover, rubber hydrochloride is in itself a tough, flexible, oil resistant, water resistant, and gas resistant material. It appears to co-act with the glycerinated paper to give a composite flexible sheet of superior oil resistance during usage as a wrapping sheet or as a receptacle. Smaller amounts of rubber'hydrochloride need be used than most other coating materials to obtain satisfactory results, and also, smaller quantities of plasticizers need be used with the rubber hydrochloride. Furthermore, the rubber hydrochlorides are readily heat scalable as well as being tough and oil resistant, and for these as well as other reasons are particularly suitable as heatsealing adhesives for sealing bags which must retain oil throughout commercial use without leakage.

In general, all types of rubber hydrochloride are suitable and are preferred to other film forming materials. However, for ease of application, I prefer the amorphous rubber hydrochloride of approximately 28 to 29.8% chlorine content, obtainable by reacting milled sheet rubber with liquefied hydrogen chloride at approximately -85 C. This material is readily soluble in aromatic hydrocarbon solventsto give'solutions of viscosity and wetting power towards glycerinated paper suitable for use with a roll coating machine or by immersion methods. Moreover, the amorphous rubber hydrochloride is more readily plasticized than the saturated crystalline rubber hydrochloride. resistance and higher flow point the crystalline, saturated rubber hydrochlorides of 30% to 33.9% chlorine content, obtainable by reacting solid sheet rubber with gaseous hydrogen chloride at above C. are used, dissolved in chlorinated solvents. Also the saturated and partially saturated rubber hydrochlorides from 27% to 33.9% chlorine obtainable by reacting solutions of rubberwith gaseous hydrogen chloride are suitable, but partially saturated rubber hydrochloride of .below 27% chlorine content are generally tacky and not 'sulficiently oil resistant for many purposes. Likewise, chlorinated rubber hydrochlorides may be used but are not generally satisfacto'ry above 40% chlorine content.

Although the preferred and superior base film forming materials for my purposes are the rubber hydrochlorides, it is possible to substitute other film forming ingredients, particularly for purposes where the paper is not to be used for creased However, for higher oil receptacles containing oils, or where the creased receptacles are not expected to stand severe conditions of usage. Moreover, by increasing the quantities of the other materials over that required for rubber hydrochloride, and/or by proper plasticization of the materials fairly satisfactory results may be obtained. Among the most satisfactory of the other materials are polymerized chloroprene, chlorinated polychloroprene, chlorinated rubber, and condensation derivatives of rubber obtainable by treating rubber with the halide of an amphoteric metal, or chlorostannic acid, particularly when these materials are themselves plasticized and coated on plasticized paper.

The inherent toughness and flexibility of thin films of rubber hydrochloride make the use of a plasticizer with it less important than for other materials. However, small amounts of plasticizer with rubber hydrochloride are of high advantage, particularly with the amorphous satu-v rated rubber hydrochloride. Preferably petroleum oil resistant plasticizers are used such as dibutyl phthalate, dimethyl phthalate, diethyl phthalate, triphenyl phosphate, butyl phthalyl butyl glycollate, methyl phthalyl ethyl glycollate, ethyl phthalyl ethyl glycollate.

The incompatibility of rubber hydrochloride with glycerine and the general non-adhesiveness of' rubber hydrochloride makes the use of a bonding agent with the rubber hydrochloride highly advantageous. The preferred bonding agent is one which is a plasticizer, which is compatible with rubber hydrochloride, which is oil resistant, and which will adhere to glycerine as well as paper.

Included in the useful bonding agents which are compatible with rubber hydrochloride are soft or hard chlorinated diphenyls (Arochlors), toluene sulphonamides (Santicizers), toluenesulphonamide-formaldehyde (Santolite MHP), soft or hard cumarone-indene resins (cumars), ester gum, rosin, dammar, copal, phenolaldehyde resins (Lewisol, Amberols, Paranol, Bakelite, etc.), and alkyd resins modified with rosin or ester gum (Lewisol L 500, 2, and 3).

The most important bonding agents for coatings which must resist oil are the petroleum oil resistant materials, including phenol-aldehyde resins, alkyds, waxfree dammar, copal, toluenesulphonamide, toluenesulphonamide formaldehyde.

' In all cases where a rubber hydrochloride is used, it is preferred to use a stabilized rubber hydrochloride, that is, a. rubber hydrochloride containing an antacid or basic material other than a zinc or iron compound. The preferred basic compounds are magnesium oxide, magnesium carbonate, sodium carbonate, calcium oxide, calcium stearate, magnesium stearate, litharge, and hexamethylene tetramine. These materials are used in amount such that an excess is always present to neutralize any acidity which may develop. They appear to retard the development of acidity as well as neutralizing acidity. For paper coatings a stabilized rubber hydrochloride is especially important in order to prevent weakening of the paper.

Various antioxidants and light resistors may be added to the rubber hydrochloride film if desired. Also waxes such .as paraffin wax, bees wax, may be used to increase water resistance with, however, some decrease in oil resistance when the wax is itself non-oil resistant. Dyes or pigments may be used to give colored films.

The invention may be more clearly understood by referring to the following examples:

EXAMPLE I Paper bags and packages for shipment and storage of oil 10HM198 IOHMZX) Parts by Parts by weiqilt Amorphous rubber hydrochloride 29.8 wei M chlori 100 Hexamethylene tetramine Phenol-aldehyde resin (Paranol LB) lgibutyl phthalate amin The paper is coated on both sides by an 'immersion and doctoring method, and solvent evaporated, care being taken to obtain a thin unbroken film extending over the surface of the glycerinated paper and effectively sealing any pinholes in the paper.

The coating is applied so as to give a very thin but uniform film over the entire surface of both sides of the paper, so that the film of rubber hydrochloride envelopes and seals in the glycerine and water in the paper. This paper is itself very suitable for general wrapping purposes. However, when the paper is to be used to make paper bags, it is advisable to apply an 1 ticularly valuable for holding oil. For this purpose, the bags are partially filled with oil and the top portion of the bag folded and sealed forming an oil, water and gas tight package. The sealed package containing oil is then in serted in a' cardboard carton.

The complete package is an inexpensive, shock resistant, heat and light protective oil container, which can be stored and shipped for from three weeks to several years in all kinds of weather without leakage of oil or contamination of the oil with moisture, moisture vapor, oxygen or other gases.

EXAMPLE II Wrapping sheets The following formula was used to coat plasticized glassine paper for the p pose of making moisture and moisture vapor and grease resistant relatively transparent wrapping sheets. The

cements were made by dissolving amorphous saturated rubber hydrochloride in tolucl, neutralizing with sodium carbonate, filtering, and then adding the resins and paraflin:

' ing and for prolonged periods of time.

Exsuru: III

Baas and packages for shipment and storage of cofiee, and the like Plasticized kraft paper (sulfate paper) was coated with a composition as follows dissolved in a volatile solvent:

Parts by weight Rubber hydrochloride (amorphous, 29% chlorine) '100 100 Glyceryl abietate ,10

Rosin 10 Dammar 15 Ethyl abietate. 5 5 Butyl stearate 5 Paraflin wax 2 2 2 Hexamethylene tetramine 1 1 I 1 Magnesium oxide 5 5 5 A strong, flexible, non-toxic, translucent, moisture and vapor resistant sheet was obtained.

EXAMPLE IV Wrapping sheets, bags, etc., for general purposes Plasticized glassine was coated with a composition as follows: a

' Parts by weight Rubber hydrochloride (amorphous,

29% chlorine) 100 Cumarone-indene resin (Cumar W /2)- 25 Chlorinated Qphenyl (Arochlor No.

4465) High melting paraffin wax w 5 5 A flexible, transparent, moisture and vapor resistant sheet was obtained.

Many of the advantages of rubber hydrohalide over other film forming materials as a coating for my plastlcized papers have been herein disclosed; other advantages will become apparent to those who carry out my invention. I do not know and do not understand all the reasons for the superiority of rubber hydrohalidw. Many of the results attained were, at least to me, surprising.

I have observed that even extremely thin films of rubber hydrochlorides of .0001" and less were highly impervious to water, water vapor, and glycerine, and believe that this property accounts in part for the ability of my coated sheets to remain flexible and oil resistant even after creas- I have also observed the good adherence of the rubber hydrochloride film layer to the glycerinated paper, and was agreeably surprised at the flexibility and imperviousness of the coated sheets at subzero temperatures and at the temperature of F,

I am aware that numerous details of the process may be varied through a wide range without departing from the principle of this invention, and I, therefore, do not propose limiting the patent granted hereon otherwise than necessitated by the prior art.

The term "extended period of time" or prolonged period of time as used in the specification and claims is intended to mean a time intervalof about three weeks or longer, such as is commonly present from the time of manufacture to time of consumption.

I claim:

1. A coated paper bag capable of retaining oil an extended period of time, comprising paper having associated therewith a relatively nonvolatile, oil-resistant softener which prevents the paper from cracking on creasing during the formation of the bag and during usage, the paper being of a type and thickness that in its 'dry unsoftened state it will crack on creasing, the softener being sealed into the paper by a thin adhering oil-proof coating covering both sides of the paper and comprising a rubber hydrochloride.

2. A coated paper bag for holding oil, the bag being of a type which is creased and in which a portion of the material of the bag is secured to an adjacent portion to form closed sides and bottom, said bag comprising bag paper having associated therewith a relatively non-volatile oil-resistant softener which prevents the paper from cracking on creasing during the formation of the bag, the softener being sealed into the paper by a thin adhering oil-proof coating covering both sides of the paper and comprising a rubber hydrochloride, the sides and bottom of the bag being secured together by an oil-proof thermoplastic composition comprising rubber hydrochloride.

3. A coated paper bag for holding oil, the bag being of a type which is creased and in which a portion of the material of thebag is secured to an adjacent portion to form closed sides and bottom, said bag comprising bag paper having associated therewith a polyhydroxy alcohol which prevents the paper from cracking on creasing during the formation of the bag, the polyhydroxy alcohol being sealed into the paper by a thin adhering oil-proof coating covering both sides of the paper and comprising a rubber hydrochloride, the sides and bottom of the bag being secured together by an oil-proof thermoplastic composition comprising rubber hydrochloride.

4. A coated paper bag for holding oil, the bag being of a type'which is creased and in which a portion of the material of the bag is secured to an adjacent portion to form closed sides and bottom, said bag comprising bag paper having associated therewith a polyglycerol which prevents the paper from cracking on creasing during the formation of the bag, the polyglycerol being sealed into the paper by a thin adhering oil-proof coating'covering both sides of the paper and comprising a rubber hydrochloride, the sides and bottom of the bag being secured together by an oil-proof thermoplastic composition comprising rubber hydrochloride.

5. A coated paper bag for holding oil, the bag being of a type which is creased and in which a portion of the material of the bag is secured to an adjacent portion to form closed sides and bottom, said bag comprising bag paper having associated therewith glycerine which prevents the paper from cracking on creasing during the formation of the bag, the glycerine being sealed into the paper by a thin adhering oil-proof coating covering both sides of the paper and comprising a rubber hydrochloride, the sides and bottom of the bag being secured together by an oil-proof thermoplastic composition comprising rubber hydrochloride.

6. A coated paper bag for holding oil, the bag being of a type which is creased and in which a portion of the material of the bag is secured to an. adjacent portion to form closed sides and bottom, said bag comprising vegetable parchment having associated therewith glycerine which prevents the paper from cracking on creasing during the formation of the bag, the glycerine being sealed into the paper by a thin adhering oil-proof coating covering both sides of the paper and comprising a rubber hydrochloride, the sides and bottom of the bag being secured together by an oil-proof thermoplastic composition comprising rubber hydrochloride.

7. A coated paper bag for holding oil, the bag being of the type which is creased and in which a portion of the material of the bag is secured to an adjacent portion to form closed sides and bottom, said bag comprising vegetable parchment in the form of a sheet of approximately .003 inch in thickness, impregnated with glycerine in the proportion of about seventeen pounds of glycerine per forty-three pounds of dry, unsoftened paper, the glycerine being sealed into the paper by a thin adhering oil-proof coating covering both sides of the paper and comprising a rubber hydrochloride and an oil-resistant p1asticizer for said rubber hydrochloride, thesides and bottom of the bag being secured together by an oil-proof thermoplastic composition comprising rubber hydrochloride.'

8. A coated paper bag capable of holding oil an extended period of time, comprising paperimpregnated with a soft, hygroscopic relatively non-volatile material which is a non-solvent for rubber hydrochloride, said hygroscopic material being present in such amount as to retain sufficient water under normal atmospheric conditions as to prevent the paper from cracking on creasing, said paper being of a type and thickness that in its dry unsoftened state it will crack on creasing, and a thin,-flexible layer of rubber hydrochloride covering and adhering to said impregnated paper in such a manner as to fill up pinholes and protect the surface.

FLOYD E. WILLIAMS. 

